The urinary incontinence is involuntary leakage of urine which can be proved objectively and defined as urinary leakage closely related to human life from social and hygiene perspectives (according to the International Incontinence Society). Now, the urinary incontinence is increasing specifically in men and women over 40 years old. Among types of urinary incontinence, stress urinary incontinence occurs most frequently and, supposedly, accounts for half or more of urinary incontinence in women. The stress urinary incontinence tends to involuntarily occur when experiencing abdominal pressure due to coughing, sneezing, lifting weights, walking for long time, singing, laughing or yelling, consequently resulting in causing suffering. Especially in women, the number of postmenopausal patients has markedly increased and it seems that the stress urinary incontinence is attributed to weakening of the pelvic floor muscle, which is caused by aging and occurs with greater frequency in women who have been pregnant or multiparous.
On the other hand, there is an overactive bladder which has drawn attention in recent years as another factor of urinary incontinence is a syndrome accompanied typically by frequent micturition or nocturia with urinary urgency as a predominant symptom and impending incontinence in certain instances, but overt causative disease thereof cannot be found in 12.4 percents of men and women aged 40 and over. (International Continence Society, 2002) This symptom has been reported to be increased with age and manifested in 20 percents of 70's and 35 percents of 80's. Also, the urinary incontinence associated with cystitis or interstitial cystitis is increasing.
Furthermore, the male-specific urinary incontinence may be developed due to disturbance of the bladder sphincter which occurs frequently in patients undergoing a total relaxation to treat prostate cancer or aftereffects suffered from indispensable dominant nerve section, aftereffects of radiation by radiotherapy for prostate cancer or prostate enlargement related surgery, or inadvertent nerve cutting happened during a surgery operation.
The group of diseases as a predominant symptom of urinary incontinence increases remarkably in male and female patients aged over 50 with igniting a social problem. A disturbance in pelvic floor muscle and flaccidity of a supporting structure such as a ligament are subjected to an operative procedure performed for the cure of female urinary incontinence on the basis of an integral theory.
However, a patient with less serious disease and a patient who prefers not to undergo surgery for any other reason have longed for ambisextrous-applicable measures capable of being relieved of physical pain by relatively-easy treatment without relying on any open surgery. As a passive way, there have been measures to absorb urine with a napkin or the like, collect urine in a urine-collecting bag worn on the penis or absorb urine with a pad or the like worn on the external genitals in case of precipitating urinary incontinence. However, these supplies must be replaced at frequent intervals and abhorrently cause unpleasant sensation and an objectionable odor in the event of attachment or replacement. Thus, there is a need for positive measures to control urination per se for preventing urinary incontinence. As an example, there have been devised a variety of methods using a device which is disposed in the urethra to prevent urinary leakage in its closed state and expedite urination in its casually open state.
Patent Literature 1 discloses a device provided in the urethra with a slit-type beaklike valve or a ball and a catheter with a valve for controlling urination of female. The device having a stylet to place a catheter in the urethra of woman is used to insert a urination tool from the body into the slit-type valve in the open state of the catheter valve, thereby enabling excretion of intravesical content.
Patent Literature 2 discloses a device comprising a bladder balloon to be fitted within the bladder, a conduit for conducting and excreting urinary flow, and an incontinence controller having an actuating valve for closing the conduit. The disclosed device is provided with a switching mechanism for operating the actuating valve by means of a spring and a manual actuating member so as to excrete urine by operating the actuating member to part a metallic valve head from the conduit and arbitrarily control incontinence by manually releasing the spring to close the conduit with the valve head.
Patent Literature 3 discloses a urination controlling device chiefly comprising a valve, which is disposed in the proximity of the bladder in the urethra. The disclosed device is used to control urination responsive to the abdominal muscle pressure with which a patient causes a muscle contraction by opening the valve with stress difference between the intravesical pressure in the bladder and the spring.
Patent Literature 4 discloses a urination controlling device comprising an intraductal coil to be inserted into the conduit and magnet-operated switching means so as to enable the switching operation of the switching means from outside. The device is intended to reliably perform closing of the urinary tract and controlling of urination.
In addition to the devices of the type set inside the body, there has been developed a device for controlling urination by arbitrarily dissolving a blocking medicament inserted in the urethra. Patent Literature 5 makes mention of inserting the medicament containing polyvinyl alcohol laced with alginate polymer or boronate polymer into the urethra to block the urethra, thereby to make a gel plug for preventing urinary incontinence. By infusing dextrose solution or the like into the gel plug when urinating, stability of gel is broken to dissolve the gel plug, consequently to allow urination.